Chromosomal nonhistone proteins (nuclear, nudleolar and chromatin-associated) will be used as antigens to elicit antibodies to human or animal colonic tissues (normal or malignant). Specificity of the individual antisera will be tested by reacting them with electrophoretically separated nuclear or chromosomal proteins transferred to nitrocellulose sheets. Proteins which form an antigen-antibody complex will be detected by staining the transfers with peroxidase-antiperoxidase reaction. Antigens specific for adenocarcinomas of the colon (human or animal) will be isolated and characterized. Two of such antigens were already detected in our laboratory. They are chromosomal nonhistone proteins m.w. 67,000 and 92,000. These two proteins were found in human adenocarcinoma cell lines HT-29 and LoVo but not in normal human colon mucosa. The m.w. 67,000 and 92,000 protein antigens will be purified and characterized. Additional tumor-associated antigens will be sought by immunizations with fractions of nuclei or chromatin. The distribution of tumor-specific or tumor-associated antigens in chromatin structure will be determined. Immunization with dehistonized chromatin preparations has been shown to elicit highly specific antibodies which recognize complexes between chromosomal nonhistone proteins and DNA. We will attempt to characterize both the protein and DNA components of these complexes and determine how they interact with each other. Antibodies to tumor specific chromosomal proteins and their complexes with DNA will be utilized as markers in studies on phenotypic changes associated with chemical carcinogenesis of the large bowel. We hope to develop techniques for immunological identification of malignant and pre-malignant cells in sectioned tissues or tissue biopsies.